FCL/sf/mw/qt: comparison src/plugins/imageformats/gif/qgifhandler.cpp

equal deleted inserted replaced

-:dee5afe5301f
+:3f74d0d4af4c
 public:
 QGIFFormat();
 ~QGIFFormat();
 int decode(QImage *image, const uchar* buffer, int length,
-int *nextFrameDelay, int *loopCount, QSize *nextSize);
+int *nextFrameDelay, int *loopCount);
+static void scan(QIODevice *device, QVector<QSize> *imageSizes, int *loopCount);
 bool newFrame;
 bool partialNewFrame;
 private:
 This function decodes some data into image changes.
 Returns the number of bytes consumed.
 */
 int QGIFFormat::decode(QImage *image, const uchar *buffer, int length,
-int *nextFrameDelay, int *loopCount, QSize *nextSize)
+int *nextFrameDelay, int *loopCount)
 {
 // We are required to state that
 //    "The Graphics Interchange Format(c) is the Copyright property of
 //    CompuServe Incorporated. GIF(sm) is a Service Mark property of
 //    CompuServe Incorporated."
 if (image->isNull()) {
 (*image) = QImage(swidth, sheight, format);
 bpl = image->bytesPerLine();
 bits = image->bits();
 memset(bits, 0, image->byteCount());
-// ### size of the upcoming frame, should rather
-// be known before decoding it.
-*nextSize = QSize(swidth, sheight);
 }
 disposePrevious(image);
 disposed = false;
 }
 }
 return initial-length;
 }
+/*!
+Scans through the data stream defined by \a device and returns the image
+sizes found in the stream in the \a imageSizes vector.
+*/
+void QGIFFormat::scan(QIODevice *device, QVector<QSize> *imageSizes, int *loopCount)
+{
+if (!device)
+return;
+qint64 oldPos = device->pos();
+if (!device->seek(0))
+return;
+int colorCount = 0;
+int localColorCount = 0;
+int globalColorCount = 0;
+int colorReadCount = 0;
+bool localColormap = false;
+bool globalColormap = false;
+int count = 0;
+int blockSize = 0;
+int imageWidth = 0;
+int imageHeight = 0;
+bool done = false;
+uchar hold[16];
+State state = Header;
+const int readBufferSize = 40960; // 40k read buffer
+QByteArray readBuffer(device->read(readBufferSize));
+if (readBuffer.isEmpty()) {
+device->seek(oldPos);
+return;
+}
+// This is a specialized version of the state machine from decode(),
+// which doesn't do any image decoding or mallocing, and has an
+// optimized way of skipping SkipBlocks, ImageDataBlocks and
+// Global/LocalColorMaps.
+while (!readBuffer.isEmpty()) {
+int length = readBuffer.size();
+const uchar *buffer = (const uchar *) readBuffer.constData();
+while (!done && length) {
+length--;
+uchar ch = *buffer++;
+switch (state) {
+case Header:
+hold[count++] = ch;
+if (count == 6) {
+state = LogicalScreenDescriptor;
+count = 0;
+}
+break;
+case LogicalScreenDescriptor:
+hold[count++] = ch;
+if (count == 7) {
+imageWidth = LM(hold[0], hold[1]);
+imageHeight = LM(hold[2], hold[3]);
+globalColormap = !!(hold[4] & 0x80);
+globalColorCount = 2 << (hold[4] & 0x7);
+count = 0;
+colorCount = globalColorCount;
+if (globalColormap) {
+int colorTableSize = 3 * globalColorCount;
+if (length >= colorTableSize) {
+// skip the global color table in one go
+length -= colorTableSize;
+buffer += colorTableSize;
+state = Introducer;
+} else {
+colorReadCount = 0;
+state = GlobalColorMap;
+}
+} else {
+state=Introducer;
+}
+}
+break;
+case GlobalColorMap:
+case LocalColorMap:
+hold[count++] = ch;
+if (count == 3) {
+if (++colorReadCount >= colorCount) {
+if (state == LocalColorMap)
+state = TableImageLZWSize;
+else
+state = Introducer;
+}
+count = 0;
+}
+break;
+case Introducer:
+hold[count++] = ch;
+switch (ch) {
+case 0x2c:
+state = ImageDescriptor;
+break;
+case 0x21:
+state = ExtensionLabel;
+break;
+case 0x3b:
+state = Done;
+break;
+default:
+done = true;
+state = Error;
+}
+break;
+case ImageDescriptor:
+hold[count++] = ch;
+if (count == 10) {
+int newLeft = LM(hold[1], hold[2]);
+int newTop = LM(hold[3], hold[4]);
+int newWidth = LM(hold[5], hold[6]);
+int newHeight = LM(hold[7], hold[8]);
+if (imageWidth/10 > qMax(newWidth,200))
+imageWidth = -1;
+if (imageHeight/10 > qMax(newHeight,200))
+imageHeight = -1;
+if (imageWidth <= 0)
+imageWidth = newLeft + newWidth;
+if (imageHeight <= 0)
+imageHeight = newTop + newHeight;
+*imageSizes << QSize(imageWidth, imageHeight);
+localColormap = !!(hold[9] & 0x80);
+localColorCount = localColormap ? (2 << (hold[9] & 0x7)) : 0;
+if (localColorCount)
+colorCount = localColorCount;
+else
+colorCount = globalColorCount;
+count = 0;
+if (localColormap) {
+int colorTableSize = 3 * localColorCount;
+if (length >= colorTableSize) {
+// skip the local color table in one go
+length -= colorTableSize;
+buffer += colorTableSize;
+state = TableImageLZWSize;
+} else {
+colorReadCount = 0;
+state = LocalColorMap;
+}
+} else {
+state = TableImageLZWSize;
+}
+}
+break;
+case TableImageLZWSize:
+if (ch > max_lzw_bits)
+state = Error;
+else
+state = ImageDataBlockSize;
+count = 0;
+break;
+case ImageDataBlockSize:
+blockSize = ch;
+if (blockSize) {
+if (length >= blockSize) {
+// we can skip the block in one go
+length -= blockSize;
+buffer += blockSize;
+count = 0;
+} else {
+state = ImageDataBlock;
+}
+} else {
+state = Introducer;
+}
+break;
+case ImageDataBlock:
+++count;
+if (count == blockSize) {
+count = 0;
+state = ImageDataBlockSize;
+}
+break;
+case ExtensionLabel:
+switch (ch) {
+case 0xf9:
+state = GraphicControlExtension;
+break;
+case 0xff:
+state = ApplicationExtension;
+break;
+default:
+state = SkipBlockSize;
+}
+count = 0;
+break;
+case ApplicationExtension:
+if (count < 11)
+hold[count] = ch;
+++count;
+if (count == hold[0] + 1) {
+if (qstrncmp((char*)(hold+1), "NETSCAPE", 8) == 0)
+state=NetscapeExtensionBlockSize;
+else
+state=SkipBlockSize;
+count = 0;
+}
+break;
+case GraphicControlExtension:
+if (count < 5)
+hold[count] = ch;
+++count;
+if (count == hold[0] + 1) {
+count = 0;
+state = SkipBlockSize;
+}
+break;
+case NetscapeExtensionBlockSize:
+blockSize = ch;
+count = 0;
+if (blockSize)
+state = NetscapeExtensionBlock;
+else
+state = Introducer;
+break;
+case NetscapeExtensionBlock:
+if (count < 3)
+hold[count] = ch;
+count++;
+if (count == blockSize) {
+*loopCount = LM(hold[1], hold[2]);
+state = SkipBlockSize;
+}
+break;
+case SkipBlockSize:
+blockSize = ch;
+count = 0;
+if (blockSize) {
+if (length >= blockSize) {
+// we can skip the block in one go
+length -= blockSize;
+buffer += blockSize;
+} else {
+state = SkipBlock;
+}
+} else {
+state = Introducer;
+}
+break;
+case SkipBlock:
+++count;
+if (count == blockSize)
+state = SkipBlockSize;
+break;
+case Done:
+done = true;
+break;
+case Error:
+device->seek(oldPos);
+return;
+}
+}
+readBuffer = device->read(readBufferSize);
+}
+device->seek(oldPos);
+return;
+}
 void QGIFFormat::fillRect(QImage *image, int col, int row, int w, int h, QRgb color)
 {
 if (w>0) {
 for (int j=0; j<h; j++) {
 QRgb *line = (QRgb*)image->scanLine(j+row);
 QGifHandler::QGifHandler()
 {
 gifFormat = new QGIFFormat;
 nextDelay = 0;
-loopCnt = 0;
+loopCnt = 1;
 frameNumber = -1;
-nextSize = QSize();
+scanIsCached = false;
 }
 QGifHandler::~QGifHandler()
 {
 delete gifFormat;
 if (buffer.isEmpty())
 break;
 }
 int decoded = gifFormat->decode(&lastImage, (const uchar *)buffer.constData(), buffer.size(),
-&nextDelay, &loopCnt, &nextSize);
+&nextDelay, &loopCnt);
 if (decoded == -1)
 break;
 buffer.remove(0, decoded);
 }
 return gifFormat->partialNewFrame;
 if (buffer.isEmpty())
 break;
 }
 int decoded = gifFormat->decode(&lastImage, (const uchar *)buffer.constData(), buffer.size(),
-&nextDelay, &loopCnt, &nextSize);
+&nextDelay, &loopCnt);
 if (decoded == -1)
 break;
 buffer.remove(0, decoded);
 }
 if (gifFormat->newFrame || (gifFormat->partialNewFrame && device()->atEnd())) {
 }
 QVariant QGifHandler::option(ImageOption option) const
 {
 if (option == Size) {
-if (imageIsComing())
+if (!scanIsCached) {
-return nextSize;
+QGIFFormat::scan(device(), &imageSizes, &loopCnt);
+scanIsCached = true;
+}
+// before the first frame is read, or we have an empty data stream
+if (frameNumber == -1)
+return (imageSizes.count() > 0) ? QVariant(imageSizes.at(0)) : QVariant();
+// after the last frame has been read, the next size is undefined
+if (frameNumber >= imageSizes.count() - 1)
+return QVariant();
+// and the last case: the size of the next frame
+return imageSizes.at(frameNumber + 1);
 } else if (option == Animation) {
 return true;
 }
 return QVariant();
 }
 return nextDelay;
 }
 int QGifHandler::imageCount() const
 {
-return 0; // Don't know
+if (!scanIsCached) {
+QGIFFormat::scan(device(), &imageSizes, &loopCnt);
+scanIsCached = true;
+}
+return imageSizes.count();
 }
 int QGifHandler::loopCount() const
 {
+if (!scanIsCached) {
+QGIFFormat::scan(device(), &imageSizes, &loopCnt);
+scanIsCached = true;
+}
 return loopCnt-1; // In GIF, loop count is iteration count, so subtract one
 }
 int QGifHandler::currentImageNumber() const
 {

branch	RCL_3
changeset 8	3f74d0d4af4c
parent 4	3b1da2848fc7